jovan belcher shot his girlfriend multiple times at the home they shared. then he drove to the training complex behind me and killed himself in front of several coaches who were trying to talk him out of it. police know what happened, now they're trying to figure out and investigate why it happened. that investigation is ongoing. police are not saying much else about a potential motive. >> i think everyone who has spoken out from family members to friends have all said that they were completely shocked by this. it seems so out of character. having said that, as you know, there's been at least six current or former nfl players that have committed suicide in just the past two years. murder-suicide unprecedented. however there are some people this morning who are speculating these tragedies could have been linked to undiagnosed concussion injuries. any truth to that? >> well, we don't know if there's truth to it, but it's certainly a natural area of inquiry. the nfl has been trying in the last couple of years to deal with the issue of concussions. as you menti